Niacinamide is the most useful ingredient in skincare that people are most confused about. Three myths follow it around, and all three are worth putting down.
Myth one: it cancels out vitamin C
This comes from research done in the 1960s, at high heat, on unbuffered solutions, over long periods. Under those conditions niacinamide and ascorbic acid can form a complex that turns the mixture yellow and irritating.
Your face is not a heated flask, and modern formulas are buffered. Products containing both have been sold for years without the problem appearing. Use them together if you want to.
Myth two: it purges
Purging is a real phenomenon, and it is specific: it happens with ingredients that speed up cell turnover, like retinoids and exfoliating acids, which bring existing microcomedones to the surface faster than they would have arrived. That is what "purging" describes.
Niacinamide does not accelerate turnover. If you break out on it, that is not a purge working itself out, it is a reaction, and the answer is to stop rather than to push through.
Myth three: it stings, so it is working
Niacinamide can contain trace nicotinic acid, which causes flushing in some people. More often, the sting comes from applying it to damp skin, which increases how much gets through at once.
The fix is the whole tip: apply it to dry skin. If your routine has it going on straight after a hydrating layer, move it.
What it actually does
Barrier support, by helping skin produce more ceramides. Oil regulation, at around five percent and above. And a genuinely useful effect on post- inflammatory marks, which is why it turns up in almost every product aimed at the shadows breakouts leave behind.
None of that is fast. The studies showing smaller-looking pores and calmer redness run eight to twelve weeks. Four weeks is the earliest anyone should expect an opinion.
How much
Five percent does nearly everything. Ten percent is not obviously better, and it is more likely to irritate. The very high percentages are marketing.